KVM: x86/mmu: Stash 'kvm' in a local variable in kvm_mmu_free_roots()

To make kvm_mmu_free_roots() a bit more readable, capture 'kvm' in a
local variable instead of doing vcpu->kvm over and over (and over).

No functional change intended.
Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Message-Id: <20200923191204.8410-1-sean.j.christopherson@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

arch/x86/kvm/mmu/mmu.c

@@ -3603,6 +3603,7 @@ static void mmu_free_root_page(struct kvm *kvm, hpa_t *root_hpa,
 void kvm_mmu_free_roots(struct kvm_vcpu *vcpu, struct kvm_mmu *mmu,
 			ulong roots_to_free)
 {
+	struct kvm *kvm = vcpu->kvm;
 	int i;
 	LIST_HEAD(invalid_list);
 	bool free_active_root = roots_to_free & KVM_MMU_ROOT_CURRENT;
@@ -3620,22 +3621,21 @@ void kvm_mmu_free_roots(struct kvm_vcpu *vcpu, struct kvm_mmu *mmu,
 			return;
 	}
 
-	spin_lock(&vcpu->kvm->mmu_lock);
+	spin_lock(&kvm->mmu_lock);
 
 	for (i = 0; i < KVM_MMU_NUM_PREV_ROOTS; i++)
 		if (roots_to_free & KVM_MMU_ROOT_PREVIOUS(i))
-			mmu_free_root_page(vcpu->kvm, &mmu->prev_roots[i].hpa,
+			mmu_free_root_page(kvm, &mmu->prev_roots[i].hpa,
 					   &invalid_list);
 
 	if (free_active_root) {
 		if (mmu->shadow_root_level >= PT64_ROOT_4LEVEL &&
 		    (mmu->root_level >= PT64_ROOT_4LEVEL || mmu->direct_map)) {
-			mmu_free_root_page(vcpu->kvm, &mmu->root_hpa,
-					   &invalid_list);
+			mmu_free_root_page(kvm, &mmu->root_hpa, &invalid_list);
 		} else {
 			for (i = 0; i < 4; ++i)
 				if (mmu->pae_root[i] != 0)
-					mmu_free_root_page(vcpu->kvm,
+					mmu_free_root_page(kvm,
 							   &mmu->pae_root[i],
 							   &invalid_list);
 			mmu->root_hpa = INVALID_PAGE;
@@ -3643,8 +3643,8 @@ void kvm_mmu_free_roots(struct kvm_vcpu *vcpu, struct kvm_mmu *mmu,
 		mmu->root_pgd = 0;
 	}
 
-	kvm_mmu_commit_zap_page(vcpu->kvm, &invalid_list);
-	spin_unlock(&vcpu->kvm->mmu_lock);
+	kvm_mmu_commit_zap_page(kvm, &invalid_list);
+	spin_unlock(&kvm->mmu_lock);
 }
 EXPORT_SYMBOL_GPL(kvm_mmu_free_roots);